Latex allergy

Latex allergy is a medical term encompassing a range of allergic reactions to the proteins present in natural rubber latex. It generally develops after repeated exposure to products containing natural rubber latex. When latex-containing medical devices or supplies come in contact with mucous membranes, the membranes may absorb latex proteins. In some susceptible people, the immune system produces antibodies that react immunologically with these antigenic proteins. Many items contain or are made from natural rubber, including shoe soles, pen grips, hot water bottles, elastic bands, rubber gloves, condoms, baby-bottle nipples, and balloons; consequently, there are many possible routes of exposure that may trigger a reaction. People with latex allergies may also have or develop allergic reactions to some fruits, such as bananas.

Signs and symptoms
Allergic reactions to latex range from Type I hypersensitivity, the most serious form of reaction, to Type IV hypersensitivity. Rate of onset is directly proportional to the degree of allergy: Type I responses will begin showing symptoms within minutes of exposure to latex, while Type IV responses may take hours or days to appear.

Most commonly, latex allergy presents with hives at the point of contact, followed by rhinitis. The most common physiological reaction to latex exposure is dermatitis at the point of contact, which gives way to soreness, itching, and redness. Angioedema is also a common response to oral, vaginal, or rectal contact.

Symptoms of more severe hypersensitivity include both local and generalized hives; feelings of faintness or impending doom; angioedema; nausea and vomiting; abdominal cramps; rhinitis; bronchospasm; and anaphylaxis. Type IV responses typically include erythema, blistering (forming vesicles and papules), itching, and crusting at the point of contact. This irritant contact dermatitis is considered a nonimmune reaction to latex. The degree of reaction is directly proportional to the duration of exposure, as well as skin temperature.

Among those with a latex allergy, 40% will experience irritant contact dermatitis; 33.1% will experience a Type I allergic reaction; 20.4% will experience Type IV allergic contact dermatitis; and 6.5% will experience both Type I and Type IV symptoms.

Occupational exposure
The prevalence of latex allergy is greater in certain populations with increased exposure and has historically been studied in this context. Specifically, regular and prolonged occupational exposure to latex is a known risk factor for the development of an allergy. Healthcare workers, dental specialists, food service workers, cosmetologists, rubber industry workers, law enforcement personnel, and painters are among some of the highest-risk occupations. It is estimated that the worldwide prevalence of latex allergy in healthcare workers is 9.7%-12.4%.

Latex allergy became a more common problem in healthcare in the 1980s and 1990s with the adoption of universal precautions, which involved frequent use of latex gloves, with the emergence of HIV/AIDs. The rates of latex allergy dropped to 4-7% in the healthcare setting with the widespread introduction of non-powdered latex gloves. On December 19, 2016, the FDA officially banned the use of powdered gloves in the US healthcare setting, citing the unnecessary burden of potential injury due to allergy. General latex avoidance protocols have been put in to place in healthcare settings in the US and many other developed countries with the switch to nitrile gloves. However, latex exposure in healthcare settings in developing countries from latex gloves or latex components of medical devices such as urinary catheters, dialysis ports, or vial stoppers, remains a significant concern.

Alternative latex exposure
While most reported allergic reactions to latex have occurred in medical settings, non-healthcare workers show similar levels of latex antibodies, suggesting that they are sensitized to natural rubber latex through other sources, both inside the home and as medical patients. In particular, individuals with chronic health concerns that lead to repeated surgeries or catheterizations thus experience greater exposure to latex allergens and may develop an allergy. Outside of hospital environments, latex allergy may develop in amateur and professional athletes whose sports equipment includes natural rubber, such as swimsuits or running shoes. Rubber basketballs, in particular, may lead to contact dermatitis on the hands and fingertips. The sensitization to latex in athletes may be accelerated by the use of topical analgesics and other agents that diminish the skin barrier and increase contact. It has also been hypothesized that young children may develop a latex allergy due to exposure in the home and school environment from objects such as rubber balloons, boots, gloves, and toys.

Spina bifida
People with spina bifida often have latex allergies. Up to 68% of children with this condition will have a reaction to latex. The mechanism of this association between spina bifida and latex allergy is not clearly defined. However, spina bifida patients may become sensitized to latex early in life as they often require frequent surgeries and medical procedures that involve exposure to latex products.

Related allergies
People who have latex allergy also may have or develop an allergic response to some plants and/or products of these plants (such as fruits). This is known as latex-fruit syndrome. Fruits (and seeds) involved in this syndrome include banana, avocado, chestnut, kiwifruit, mango, passionfruit, fig, strawberry, papaya, apple, melon, celery, potato, tomato, carrot, and soy. The proteins in these fruits are similar to latex proteins. Hevein-like protein domains are a possible cause for allergen cross-reactivity between latex and banana or fruits in general.

Natural rubber latex contains several conformational epitopes located on several enzymes such as Hev b 1, Hev b 2, Hev b 4, Hev b 5 and Hev b 6.02.

FITkit is a latex allergen testing method for quantification of the major natural rubber latex specific allergens: Hev b 1, Hev b 3, Hev b 5, and Hev b 6.02.

Prevention
The most effective form of primary prevention towards latex sensitization is limiting or completely avoiding contact with latex, particularly among children with risk factors such as spina bifida. The limitation of powdered latex glove use in hospital settings has also proven an effective primary prevention strategy among adult health care workers, and as secondary prevention for sensitized individuals.

Epidemiology
Latex allergy is uncommon in the general population, at least compared to high-risk groups such as hospital workers and spina bifida patients. Estimates suggest a worldwide prevalence of around 4.3% among the general population. Between 1% and 6% of the general population in the United States has latex allergy; assays of antibody levels in the blood suggest that 2.7 million to 16 million Americans are affected by some form of latex sensitivity. Females are approximately three times as likely as males to have latex allergies. Possible risk factors for the female population include increased employment in high-risk occupations and enhanced histamine release caused by female hormones.

Alternatives
Alternatives to latex include: The first polyurethane condoms, designed for people with latex allergies, were produced in 1994.
 * Synthetic rubbers (such as elastane, neoprene, nitrile) and artificially synthesized polyisoprene latex, which do not contain the proteins from the Hevea brasiliensis tree.
 * Products made from guayule natural rubber emulsions, which also do not contain the proteins from the Hevea rubber tree, and do not cause allergy in persons sensitized to Hevea proteins.
 * Alternative materials like Vytex Natural Rubber Latex which reduce exposure to latex allergens while otherwise retaining the properties of natural rubber; these are made using chemical treatment to reduce the amount of antigenic proteins in Hevea latex.
 * Polyurethane.

Some people are so sensitive that they may still have a reaction to replacement products made from alternative materials. This can occur when the alternative products are manufactured in the same facility as latex-containing products, leaving trace quantities of natural rubber latex on the non-latex products.